Methods and devices for crossing chronic total occlusions

ABSTRACT

The present disclosure is directed to a method of facilitating treatment via a vascular wall defining a vascular lumen containing an occlusion therein. The method may include providing an intravascular device having a distal portion and a longitudinal axis and inserting the intravascular device into the vascular lumen. The method may further include positioning the distal portion in the vascular wall, rotating the intravascular device about the longitudinal axis, and advancing the intravascular device within the vascular wall.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 14/156,949, filed Jan. 16, 2014, which is acontinuation application of U.S. patent application Ser. No. 12/289,154,filed Oct. 21, 2008, which claims the benefit of U.S. ProvisionalApplication No. 60/999,879, filed Oct. 22, 2007, the completedisclosures of which are herein incorporated by reference.

FIELD OF THE INVENTION

The inventions described herein relate to devices and associated methodsfor the treatment of chronic total occlusions. More particularly, theinventions described herein relate to devices and methods for crossingchronic total occlusions and establishing a pathway blood flow past thechronic total occlusions.

BACKGROUND OF THE INVENTION

Due to age, high cholesterol and other contributing factors, a largepercentage of the population has arterial atherosclerosis that totallyoccludes portions of the patient's vasculature and presents significantrisks to patient health. For example, in the case of a total occlusionof a coronary artery, the result may be painful angina, loss of cardiactissue or patient death. In another example, complete occlusion of thefemoral and/or popliteal arteries in the leg may result in limbthreatening ischemia and limb amputation.

Commonly known endovascular devices and techniques are eitherinefficient (time consuming procedure), have a high risk of perforatinga vessel (poor safety) or fail to cross the occlusion (poor efficacy).Physicians currently have difficulty visualizing the native vessellumen, can not accurately direct endovascular devices toward thevisualized lumen, or fail to advance devices through the lesion. Bypasssurgery is often the preferred treatment for patients with chronic totalocclusions, but less invasive techniques would be preferred.

Described herein are devices and methods employed to exploit thevascular wall of a vascular lumen for the purpose of bypassing a totalocclusion of an artery. Exploitation of a vascular wall may involve thepassage of an endovascular device into and out of said wall which iscommonly and interchangeable described as false lumen access, intramuralaccess, submedial access or in the case of this disclosure, subintimalaccess.

BRIEF SUMMARY

Described herein are devices and methods employed to exploit thevascular wall of a vascular lumen for the purpose of bypassing a totalocclusion of an artery. Exploitation of a vascular wall may involve thepassage of an endovascular device into and out of said wall which iscommonly and interchangeable described as false lumen access, intramuralaccess, submedial access or in the case of this disclosure, subintimalaccess.

In one aspect, the present disclosure is directed to a method offacilitating treatment via a vascular wall defining a vascular lumencontaining an occlusion therein. The method may include providing anintravascular device having a distal portion and a longitudinal axis andinserting the intravascular device into the vascular lumen. The methodmay further include positioning the distal portion in the vascular wall,rotating the intravascular device about the longitudinal axis, andadvancing the intravascular device within the vascular wall.

In another aspect, the present disclosure is direct to a device forfacilitating treatment via a vascular wall defining a vascular lumencontaining an occlusion therein. The device may include a shaft having adistal end and a proximal end. The shaft may include a coil having aplurality of filars wound in a helical shape, the coil extending fromthe distal end of the shaft to the proximal end of the shaft, and asleeve, having a proximal end and a distal end, the sleeve extendingfrom the distal end of the shaft and covering a portion of the coil. Thedevice may further include a tip fixed to the distal end of the shaft,and a hub fixed to the proximal end of the shaft.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of an artery.

FIG. 2 is an additional view of the artery shown in the previous figure.

FIG. 3 is an additional view of the artery shown in the previous figure.

FIG. 4 is an additional view of the artery shown in the previous figure.

FIG. 5 is a cross-sectional view of an artery.

FIG. 6 is an additional view of the artery shown in the previous figure.

FIG. 7 is a partial cross-sectional view of an exemplary crossingdevice.

FIG. 8 is a plan view showing an assembly including the crossing deviceshown in the previous figure.

FIG. 9 is a plan view of the assembly shown in the previous figure.

FIG. 10 is a cross-sectional view of the assembly shown in the previousfigure.

FIG. 11 is a cross sectional view of the handle assembly shown in theprevious figure.

FIG. 12 is a partial cross-sectional view showing a guidewire that isdisposed in a lumen defined by a shaft of a crossing device.

FIG. 13 is an additional view of the guidewire and crossing device shownin the previous figure.

FIG. 14 is a plan view showing a heart including a coronary artery.

FIG. 15A is an enlarged view showing a portion of the heart shown in theprevious figure.

FIG. 15B is an enlarged plan view of a crossing device shown in FIG.15A.

FIG. 16A is an additional view showing a crossing device disposed in aheart.

FIG. 16B is an enlarged plan view of a crossing device shown in FIG.16A.

FIG. 17A is an enlarged view showing a portion of a heart and a crossingdevice that is extending into a proximal segment of a coronary artery ofthe heart.

FIG. 17B is a representation of a fluoroscopic display produced whenradiopaque fluid has been injected into the body from the distal end ofa crossing device while the distal end of the crossing device isdisposed in the true lumen of a coronary artery.

FIG. 18A is an enlarged view showing a portion of a heart and a crossingdevice that is extending into a proximal segment of a coronary artery ofthe heart.

FIG. 18B is a representation of a fluoroscopic display produced whenradiopaque fluid has been injected into the body from the distal end ofa crossing device while the distal end of the crossing device isdisposed in the subintimal space of a coronary artery.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

FIG. 1 is a cross-sectional view of an artery 102 having a wall 126. InFIG. 1, wall 126 of artery 102 is shown having three layers. Theoutermost layer of wall 126 is the adventitia 105 and the innermostlayer of wall 126 is the intima 107. The tissues extending betweenintima 107 and adventitia 105 may be collectively referred to as themedia 109. For purposes of illustration, intima 107, media 109 andadventitia 105 are each shown as a single homogenous layer in FIG. 1. Inthe human body, however, the intima and the media each comprise a numberof sub-layers. The transition between the external most portion of theintima and the internal most portion of the media is sometimes referredto as the subintimal space.

Intima 107 defines a true lumen 106 of artery 102. In FIG. 1, anocclusion 108 is shown blocking true lumen 106. Occlusion 108 dividestrue lumen 106 into a proximal segment 103 and a distal segment 104. Acrossing device 120 is disposed in proximal segment 103 of true lumen106. Crossing device 120 may be used to establish a channel betweenproximal segment 103 and distal segment 104. Crossing device 120 of FIG.1 comprises a tip 124 that is fixed to a distal end of a shaft 122.

FIG. 2 is an additional view of artery 102 shown in the previous figure.In the embodiment of FIG. 2, the distal end of crossing device 120 hasbeen advanced in a distal direction so that tip 124 is disposed insubintimal space 128. With reference to FIG. 2, it will be appreciatedthat tip 124 has passed through intima 107 and is disposed betweenintima 107 and adventitia 105 of artery 102. The embodiment of FIG. 2and other embodiments described herewithin show access to the subintimalspace 128 by way of example, not limitation, as the crossing device 120may alternatively pass through the occlusion 108 thus remaining disposedin the true lumen 106.

In the embodiment of FIG. 2, shaft 122 of crossing device 120 defines alumen 130. Lumen 130 may be used to deliver fluids into the body. Forexample, radiopaque fluid may be injected through lumen 130 and intosubintimal space 128. In some useful embodiments, lumen 130 isdimensioned to receive a guidewire.

FIG. 3 is an additional view of artery 102 shown in the previous figure.In the embodiment of FIG. 3, the distal end of crossing device 120 hasbeen advanced so that tip 124 has moved in an axial direction throughsubintimal space 128. With reference to FIG. 3, it will be appreciatedthat tip 124 has moved distally past occlusion 108. In FIG. 3, tip 124is shown residing between intima 107 and adventitia 105 of artery 102.Axial advancement of tip 124 may cause blunt dissection of the layersforming wall 126 of artery 102. Alternatively, the tip may cause bluntdissection of the materials comprising the occlusion 108 (not shown).

In some useful methods in accordance with the present disclosure,crossing device 120 is rotated about it's longitudinal axis and moved ina direction parallel to it's longitudinal axis simultaneously. When thisis the case, rotation of crossing device 120 may reduce resistance tothe axial advancement of crossing device 120. These methods takeadvantage of the fact that the kinetic coefficient of friction isusually less than the static coefficient of friction for a givenfrictional interface. Rotating crossing device 120 assures that thecoefficient of friction at the interface between the crossing device andthe surround tissue will be a kinetic coefficient of friction and not astatic coefficient of friction.

FIG. 4 is an additional view of artery 102 shown in the previous figure.In the embodiment of FIG. 4, crossing device 120 has been withdrawn fromtrue lumen 106 of artery 102. With reference to FIG. 4, it will beappreciated that a guidewire 132 remains in the position formerlyoccupied by crossing device 120.

The position of guidewire 132 shown in FIG. 4 may be achieved usingcrossing device 120. Guidewire 132 may be positioned, for example, byfirst placing crossing device 120 in the position shown in the previousfigure, then advancing guidewire 132 through lumen 130 defined by shaft122 of crossing device 120. Alternately, guidewire 132 may be disposedwithin lumen 130 while crossing device 120 is advanced through thevasculature of a patient. When this is the case, guidewire 132 may beused to aid in the process of steering crossing device 120 through thevasculature.

With guidewire 132 in the position shown in FIG. 4, guidewire 132 may beused to direct other devices to subintimal space 128. For example, acatheter may be advanced over guidewire 132 until the distal end of thecatheter is disposed in subintimal space 128. After reaching thesubintimal space, the catheter may be used to dilate subintimal space128. Examples of catheters that may be used to dilate the subintimalspace include balloon catheters and atherectomy catheters.

FIG. 5 is a cross sectional view of an artery 202 having a wall 226. InFIG. 5, a crossing device 220 is shown extending through subintimalspace 228 and around an occlusion 208. In FIG. 5, occlusion 208 is shownblocking a true lumen 206 defined by an intima 207 of wall 226.Occlusion 208 divides true lumen 206 into a proximal segment 203 and adistal segment 204. When a crossing member in accordance with someembodiments of the present disclosure is advanced through the subintimalspace of an artery, the distal end of the crossing device may penetratethe intima and enter the distal segment of the true lumen afteradvancing beyond an occlusion.

In the embodiment of FIG. 5, a tip 224 of crossing device 220 isdisposed in distal segment 204. Accordingly, it will be appreciated thatcrossing device 220 has pierced intima 207 distally of occlusion 208 andentered distal segment 204 of artery 202. In FIG. 5, shaft 222 is shownextending through intima 207 and subintimal space 228. Shaft 222 ofcrossing device 220 may define a lumen 230.

FIG. 6 is an additional view of artery 202 shown in the previous figure.In the embodiment of FIG. 6, crossing device 220 has been withdrawnleaving a guidewire 232 in the position shown in FIG. 6.

The position of guidewire 232 shown in FIG. 6 may be achieved usingcrossing device 220. Guidewire 232 may be positioned, for example, byfirst placing crossing device 220 in the position shown in the previousfigure, then advancing guidewire 232 through lumen 230 defined by shaft222 of crossing device 220. Alternately, guidewire 232 may be disposedwithin lumen 230 while crossing device 220 is advanced through thevasculature of a patient. When this is the case, guidewire 232 may beused to aid in the process of steering crossing device 220 through thevasculature of a patient.

Devices such as balloon angioplasty catheters and atherectomy cathetersmay be advanced over guidewire 232 and into subintimal space 228. Inthis way, these devices may be used in conjunction with guidewire 232 toestablish a blood flow path between proximal segment 203 of true lumen206 and distal segment 204 of true lumen 206. This path allows blood toflow through subintimal space 228 and around occlusion 208.

FIG. 7 is a partial cross-sectional view of an exemplary crossing device320. Crossing device 320 of FIG. 7 comprises a tip 324 that is fixed toa distal end of a shaft 322. In the exemplary embodiment of FIG. 7,shaft 322 comprises a coil 334, a sleeve 336, a tubular body 338, and asheath 344.

Tip 324 is fixed to a distal portion of coil 334. Coil 334 comprises aplurality of filars 342 that are wound in a generally helical shape. Insome useful embodiments of crossing device 320, coil 334 compriseseight, nine or ten filars wound into the shape illustrated in FIG. 7.Crossing device 320 includes a sleeve 336 that is disposed about aportion of coil 334. Sleeve 336 may comprise, for example, PET shrinktubing, i.e. polyethylene terephthalate.

Sleeve 336 and coil 334 both extend into a lumen defined by a tubularbody 338. Tubular body 338 may comprise, for example hypodermic tubingformed of Nitinol, i.e. nickel titanium. With reference to FIG. 7, itwill be appreciated that a proximal portion of sleeve 336 is disposedbetween tubular body 338 and coil 334. In some embodiments of crossingdevice 320, a distal portion of tubular body 338 defines a helical cut.This helical cut may be formed, for example, using a laser cuttingprocess. The helical cut may be shaped and dimensioned to provide anadvantageous transition in lateral stiffness proximate the distal end oftubular body 338.

A proximal portion of coil 334 extends proximally beyond the distal endof tubular body 338. A hub 346 is fixed to a proximal portion of coil334 and a proximal portion of tubular body 338. Hub 346 may comprise,for example, a luer fitting. Sheath 344 is disposed about a portion oftubular body 338 and a portion of sleeve 336. In some embodiments ofcrossing device 320, sheath 344 comprises HYTREL, a thermoplasticelastomer.

With reference to FIG. 7, it will be appreciated that tubular body 338,coil 334, sleeve 336, and sheath 344 each have a proximal end and adistal end. The proximal end of sheath 344 is disposed between theproximal end of tubular body 338 and the proximal end of sleeve 336. Thedistal end of sleeve 336 is positioned proximate tip 324 that is fixedto the distal end of coil 334. The distal end of sheath 344 is locatedbetween the distal end of tubular body 338 and the distal end of sleeve336. With reference to FIG. 7, it will be appreciated that sheath 344overlays the distal end of tubular body 338.

With reference to FIG. 7, it will be appreciate that tip 324 has agenerally rounded shape. The generally rounded shape of tip 324 mayreduce the likelihood that crossing device 320 will penetrate theadventitia of an artery. Tip 324 may be formed from a suitable metallicmaterial including but not limited to stainless steel, silver solder,and braze. Tip 324 may also be formed from suitable polymeric materialsor adhesives including but not limited to polycarbonate, polyethyleneand epoxy. In some embodiments of crossing device 320, outer surface 340of tip 324 comprises a generally non-abrasive surface. For example,outer surface 340 may have a surface roughness of 25 micrometers orless. A tip member having a relatively smooth outer surface may reducethe likelihood that the tip member will abrade the adventitia of anartery.

FIG. 8 is a plan view showing an assembly 348 including crossing device320 shown in the previous figure. In the embodiment of FIG. 8, a handleassembly 350 is coupled to crossing device 320. In FIG. 8, handleassembly 350 is shown disposed about a proximal portion of shaft 322 ofcrossing device 320. Handle assembly 350 comprises a handle body 352 anda handle cap 354.

In some useful embodiments in accordance with the present disclosure,handle assembly 350 is long enough to receive the thumb and for fingersof a physician's right and left hands. When this is the case, aphysician can use two hands to rotate handle assembly 350. In theembodiment of FIG. 8, grooves 356 are formed in handle body 352 andhandle cap 354. Grooves 356 may improve the physician's ability to griphandle assembly 350.

FIG. 9 is an additional plan view showing assembly 348 shown in theprevious figure. In FIG. 9, a proximal portion of handle assembly 350 ispositioned between the thumb and forefinger of a left hand 358. A distalportion of handle assembly 350 is disposed between the thumb andforefinger of a right hand 360.

In some useful methods, crossing device 320 is rotated and axiallyadvanced simultaneously. Rotation of crossing device 320 can be achievedby rolling handle assembly 350 between the thumb and forefinger onehand. Two hands can also be used as shown in FIG. 9. Rotating crossingdevice 320 assures that the coefficient of friction at the interfacebetween the crossing device and the surround tissue will be a kineticcoefficient of friction and not a static coefficient of friction.

In some useful methods in accordance with the present disclosure,crossing device 320 is rotated at a rotational speed of 2 to 200revolutions per minute. In some particularly useful methods inaccordance with the present disclosure, crossing device 320 is rotatedat a rotational speed of 50 and 150 revolutions per minute. Crossingdevice 320 may be rotated by hand as depicted in FIG. 9. It is alsocontemplated that a mechanical device (e.g., an electric motor) may beused to rotate crossing device 320.

FIG. 10 is a cross-sectional view of assembly 348 shown in the previousfigure. With reference to FIG. 10 it will be appreciated that handleassembly 350 is disposed about sheath 344, tubular body 338, sleeve 336and coil 334.

FIG. 11 is a cross sectional view of handle assembly 350 shown in theprevious figure. With reference to FIG. 11, it will be appreciated thathandle assembly 350 includes a plurality of grip sleeves 362 and aplurality of spacers 364. In the embodiment of FIG. 11, handle cap 354includes male threads 366 that engage female threads 368 in handle body352.

When handle cap 354 is rotated relative to handle body 352, the threadsproduce relative longitudinal motion between handle cap 354 and handlebody 352. In other words, handle cap 354 can be screwed into handle body352. As handle cap 354 is advanced into handle body 352, the inner endof handle cap 354 applies a compressive force to grip sleeves 362. Gripsleeves 362 are made from an elastomeric material. The compressionforces applied to grip sleeves 362 by handle body 352 and handle cap 354cause grip sleeves 362 to bulge. The bulging of grip sleeves 362 causesgrip sleeves 362 to grip shaft 322 of crossing device 320.

The force that each grip sleeve 362 applies to the shaft is generallyequally distributed about the circumference of the shaft. When this isthe case, the likelihood that the shaft will be crushed by the gripsleeves is reduced. At the same time, the grip sleeves provide aninterface that allows significant torque to be applied to the shaft whenthe handle is rotated.

FIG. 12 is a partial cross-sectional view showing a guidewire 432 thatis disposed in a lumen 430 defined by a shaft 422 of a crossing device420. FIG. 13 is an additional view showing guidewire 432 and crossingdevice 420 shown in FIG. 12. In some embodiments of crossing device 420,shaft 422 defines a lumen 430. When this is the case, a guidewire may beinserted into the lumen. The guidewire may be used to steer the crossingdevice. The guidewire may remain inside the lumen until it is needed forsteering. When steering is needed, the guidewire may be advanced so thata portion of the guidewire extends beyond the distal end of the crossingdevice. A distal portion of the guidewire may then be advanced in thedirection that the physician wishes to advance crossing device 420.

In the embodiment of FIG. 13, guidewire 432 has been distally advanced(relative to the position shown in FIG. 12). With reference to FIG. 13,it will be appreciated that a distal portion 470 of guidewire 432 isextending beyond the distal end of crossing device 420. In theembodiment of FIG. 13, distal portion 470 of guidewire 432 is biased toassume a generally curved shape when it is unrestrained by crossingdevice 420.

In the embodiment of FIG. 13, there are at least two degrees of freedombetween guidewire 432 and crossing device 420. First, guidewire 432 andcrossing device 420 are free to rotate relative to one another. Second,guidewire 432 and crossing device 420 are free to move in a longitudinaldirection relative to one another. It is sometimes desirable to useguidewire 432 as an aid in directing crossing device 420 through thevasculature of a patient. When this is the case, distal portion 470 ofguidewire 432 may be advanced beyond the distal end of crossing device420. Guidewire 432 may then be rotated until distal portion 470 ofguidewire 432 assumes a desired orientation.

FIG. 14 shows a heart 500 including a coronary artery 502. An occlusion508 is disposed in coronary artery 502. Occlusion 508 divides a lumen ofcoronary artery 502 into a proximal segment 503 and a distal segment504. The proximal segment 503 may be easily accessed using endovasculardevices and has adequate blood flow to supply the cardiac muscle. Thedistal segment 504 is not easily accessed with interventional devicesand has significantly reduced blood flow as compared to proximal segment503.

FIG. 15A is an enlarged view showing a portion of heart 500 shown in theprevious figure. In FIG. 15A, a crossing device 520 is disposed inproximal segment 503 of coronary artery 502. FIG. 15B is an enlargedplan view of crossing device 520 shown in FIG. 15A. Crossing device 520comprises a tip 524 and a shaft 522.

FIG. 16A is an additional view showing crossing device 520 disposed inheart 500. FIG. 16B is an enlarged plan view of crossing device 520shown in FIG. 16A. In FIGS. 16A and 16B crossing device 520 has beenrotated approximately ninety degrees relative to the position shown inFIGS. 15A and 15B.

Some useful methods in accordance with the present disclosure includethe step of rotating crossing device 520. When the proximal portion of acrossing device is rotated, it may be desirable to confirm that thedistal end of the crossing device is also rotating.

Many physicians have experience using guidewires. These physicians areaware that twisting the proximal end of a guidewire when the distal endof the guidewire is fixed may cause the guidewire to break due totwisting. Accordingly, many physicians may be hesitant to rotate anintravascular device more than a few revolutions unless they are certainthat the distal end of the device is free to rotate.

One method for determining whether the tip of a crossing member isrotating may be described with reference to FIGS. 15A, 15B, 16A and 16B.As shown in the figures, crossing member 520 comprises a tip 524 fixedto the distal end of a shaft 522. Tip 524 comprises a radiopaque marker572. Radiopaque marker 572 has a face 574 and an edge 576. Face 574 hasa width W and a length L. Edge 576 has a length L and a thickness T. Insome useful embodiments of crossing device 520, thickness T ofradiopaque marker 572 is smaller than both length L and width W. Whenthis is the case, radiopaque marker 572 may be used to provide aphysician with visual feedback indicating that tip 524 of crossingdevice 520 is rotating.

During rotation of crossing device 520, the shape of radiopaque markerprovides visual feedback assuring the physician that the tip of thecrossing member is rotating as the physician rotates the proximalportion of the crossing member. Radiopaque marker 572 provides twodifferent appearances while it is being rotated and observed usingfluoroscopic methods. When edge 576 of radiopaque marker is viewed on afluoroscopic display a first appearance is achieved. When face 574 ofradiopaque marker 572 is viewed, it provides a second appearance on thefluoroscopic display. With reference to the figures, it will beappreciate that the first appearance has a smaller footprint than thesecond appearance. When the appearance of radiopaque marker 572 isalternating between the first appearance and the second appearance, thephysician can infer that tip 524 is rotating. This visual feedbackallows the physician to confirm that the distal end of crossing memberis rotating.

FIGS. 17A and 18A each show a crossing device 520 comprising a tip 524fixed to a shaft 522. Tip 524 comprises a radiopaque marker 572. Tip 524of crossing device 520 has been advanced through a proximal segment 503of a coronary artery 502. With reference to FIGS. 17A and 18A, it willbe appreciated that tip 524 is near wall 526 of coronary artery 502 andan occlusion 508 that is located in the true lumen of coronary artery502. When a surgical procedure is viewed on a fluoroscope, it may bedifficult for the physician to determine whether or not tip 524 isdisposed in the subintimal space of coronary artery 502. Methods fordetermining whether the tip is disposed in the subintimal space may bedescribed with reference to FIGS. 17 and 18.

For example, one method in accordance with the present disclosure mayinclude the steps of positioning the distal end of a crossing device ina position that may or may not be in the subintimal space of an arteryand injecting radiopaque fluid into the body from the distal end ofcrossing device 520. If the radiopaque fluid remains in a localized area(e.g., in the subintimal space) then a physician viewing the radiopaquefluid on a fluoroscopic display can infer that the distal end of thecrossing device is disposed in the subintimal space. If the radiopaquefluid rapidly enters the bloodstream and is carried through thevasculature, then the physician can infer that the distal end of thecrossing device is disposed in the true lumen of the artery.

FIG. 17B is a representation of a fluoroscopic display 578 produced whenradiopaque fluid has been injected into the body from the distal end ofcrossing device 520 while tip 524 is disposed in the true lumen ofcoronary artery 502. In FIG. 17B, the radiopaque fluid 580 has rapidlyentered the bloodstream and has cause the vasculature in fluidcommunication with proximal segment 503 to become illuminated onfluoroscopic display 578. Radiopaque marker 572 is also visible influoroscopic display 578.

FIG. 18B is a representation of a fluoroscopic display 578 produced whenradiopaque fluid has been injected into the body from the distal end ofcrossing device 520 while tip 524 is disposed in the subintimal space ofcoronary artery 502. In FIG. 18B, the radiopaque fluid 580 is disposedin a localized area (i.e., in the subintimal space). Radiopaque marker572 is also visible in fluoroscopic display 578.

Additional methods are also contemplated. For example, negative pressure(i.e., sub atmospheric pressure) may be applied to the lumen defined bycrossing device 520. The physician may observe the results of thisapplication of negative pressure. If a partial vacuum is produced andlittle or no blood is drawn through the lumen, then the physician caninfer that the distal end of the lumen is located in the subintimalspace. If, on the other hand, blood is drawn through the lumen of thecrossing member, then the physician can infer that the distal end of thecrossing member is disposed in the true lumen of a blood vessel.

What is claimed is:
 1. A device for facilitating treatment via avascular wall defining a vascular lumen containing an occlusion therein,the device comprising: a crossing device including a shaft, a hub fixedat a proximal end of the shaft, and an enlarged tip fixed at a distalend of the shaft, the shaft of the crossing device including: a helicalcoil extending from the proximal end of the shaft to the distal end ofthe shaft; a polymeric sleeve extending proximally from the enlarged tipand covering at least a portion of the coil; and a metallic hypotubedisposed over a proximal portion of the helical coil; and a handleassembly coupled to the shaft of the crossing device such that rotationof the handle assembly exerts rotational motion on the crossing device;wherein the shaft extends entirely through the handle assembly anddistally therefrom.
 2. The device of claim 1, wherein the handleassembly is configured to grip an outer surface of the shaft.
 3. Thedevice of claim 2, wherein the handle assembly includes a handle bodyand a handle cap threadably coupled to the handle body.
 4. The device ofclaim 3, wherein rotation of the handle cap relative to and toward thehandle body causes the handle assembly to grip the outer surface of theshaft.
 5. The device of claim 2, wherein the handle assembly ispositioned about the metallic hypotube.
 6. The device of claim 1,wherein the hub is disposed proximal of the handle assembly.
 7. Thedevice of claim 1, wherein a guidewire lumen extends through the shaftto an opening in the enlarged tip.
 8. The device of claim 7, wherein theopening opens to an exterior of the shaft.
 9. The device of claim 8,wherein the guidewire lumen extends through the hub.
 10. The device ofclaim 1, wherein the metallic hypotube extends proximal of the handleassembly.
 11. The device of claim 1, where the hub is fixed to aproximal portion of the metallic hypotube.
 12. The device of claim 11,wherein the hub is fixed to a proximal portion of the helical coil. 13.The device of claim 1, wherein the enlarged tip has a generally roundedshape.
 14. The device of claim 1, wherein the coil includes a pluralityof filars.
 15. The device of claim 14, wherein the plurality of filarsis eight, nine, or ten filars.
 16. The device of claim 1, wherein theenlarged tip is a metallic material.
 17. The device of claim 1, whereinan outer surface of the enlarged tip is non-abrasive.
 18. The device ofclaim 1, wherein the enlarged tip includes a radiopaque marker havingtwo different fluoroscopic appearances when the enlarged tip is rotated.19. The device of claim 18, wherein a first fluoroscopic appearance ofthe radiopaque marker has a smaller footprint that a second fluoroscopicappearance of the radiopaque marker.
 20. The device of claim 1, whereina distal portion of the metallic hypotube includes a helical cut formedtherein to provide a transition in lateral stiffness proximate a distalend of the metallic hypotube.